First off, I’m a college student but in July me and my girlfriend are celebrating our five year anniversary, and I want to propose on our vacation (she’s never been to the ocean, so we’re going to this really nice beach in maine). I obviously can’t afford a real ring, and don’t have the credit for loans. I’ve looked into it a lot, and wanted to get some opinions on a simulant diamond. It’s from Diamond Nexus Labs (http://www.diamondnexuslabs.com/jewelry/product_info.php?cPath=3_135&products_id=51), and they look good to me, but I don’t know much about gems. I was thinking of buying a loose princess cut diamond there, and getting her a platinum setting. Would you be able to notice that it wasn’t a real diamond?
My budget is within 2000 if I plan to propose in July, and I’ve talked to my girlfriend about it. When I explained to her my financial limit, she said she doesn’t really care if it’s real, just as long as it is “really sparkly” or something. And from what we’ve talked about, I don’t think a colored stone is an option
Thanks to everyone that answered. I’ve decided the best thing to do is show her everything everyone has said, and let her decide herself what she wants to do.
Kansieo.com

I don’t know that I’d notice, but I would be upset if I didn’t know. Personally, I’d prefer a cheaper gem (not necessarily a diamond) that’s real than a lab created one.
EDIT: If she’s okay with it, go for it. You just may want to be looking at them in person, rather than online though for the sparkle factor